Communication systems operating over a wide range of frequencies, modulation techniques, multiplexing techniques, error correction techniques, protocols, and network topologies are known in the state of the art. Many recent papers have described numerous techniques for wireless transmission of two way, switched narrow band services and in addition there has been proposed some form of television distribution or communication distribution utilizing devices in the millimeter wave frequency band, which is between 27 GHz and 300 GHz using short range cellular transmitters covering small areas. These small areas are covered by the short range and serviced by the cellular base station transmitters which may be fed by, for example, an underground cable in the same manner as cellular radio. This distribution may also be made using microwaves converted at the local base stations to millimeter waves for local distribution. Distribution to millimeter waves stations may also be done by a fiber optics system or a satellite distribution system.
A discussion of millimeter wave stations appears in IEEE Spectrum of June, 1982, pages 54-59, entitled , "low power television short range low cost TV stations are in the offering as the FCC prepares to establish broadcast requirements". A U.S. Pat. No. 4,747,160 entitled "Low Power Multi-Function Cellular Television System" of Bossard describes a low power, point to multipoint cellular television system operating in a 27.5 to 29.5 gigahertz frequency band using omni directional antennas. A 29 GHz-2 point radio system for local distribution is described, for example, in the British Telecom Technical Journal, Volume 2, No. 1, January 1984, entitled, "29 Gigahertz-2 Point Radio Systems for Local Distributions" by S. A. Mohamed and M. Pilgrim. A low power, short range point to multipoint communication system of Langston is described in U.S. Pat. No. 6,006,089 originally filed Nov. 28, 1994. This application describes a system wherein at each node there is located an antenna system for radiating the same frequency signals a plurality of times about each node to provide spectrum reuse within each node location. The system would include subscriber receivers adapted to receive one of the polarized signals and wherein the receiver may reply back. The nodal base station transmitters transmitting the signals would have a receiving antenna system adapted to receive polarized signals from the subscriber. This application is incorporated herein by reference.
Previous two-way point-to-multipoint systems include cellular telephone systems, wireless local loop systems and satellite communication systems. Cellular systems and local loop systems frequently use sectored nodes or hubs but do not reuse the same frequency at a given node or hub. LMDS multipoint systems may use band splitting between sectors or alternating frequency channels between sectors. Satellite systems do not afford sectoring and reuse of frequency because of directivity requirements of the path. No known system is currently using 100% frequency reuse at each sectored node or hub other than that in the above cited Langston application. In a Shindo reference entitled, "Radio Subscriber Loop System for High-Speed Digital Communications," IEEE 1981 International Conference on Communications, pages 66.1.1 to 66.1.5 Vol. 3 in particular on page 66.1.2 under frequency reuse, they cite four frequency sectors a, b, c, and d, and state that in order to reduce the interference areas, polarization diversity or sector diversity shown in FIG. 2(b) can be adapted. The four sectors in the nodes are different frequency and are not of alternating polarization. There is no suggestion alternating the polarization about the node as in applicant's above cited application.
In another reference of Murakami, et al. entitled "A Multiple Access Digital Microwave Radio System for Local Subscribers" in the IEEE 1983, IEEE International Conference on Communications: Integrating Communication for World Progress (ICC '83), pages B 2.5(1) to B 2.5(7) (p. 380-6, Vol. 1), there are two or three subchannel frequencies and two polarizations. One-half of the node is at vertical, the other half of the node is at horizontal polarization. In another reference of Manichaikul, et al. entitled, "RAPAC-A Point to Multipoint Digital Radio System for Local Distribution" in the IEEE 1983, IEEE International Conference on Communications: Integrating Communication for World Progress (ICC '83), pages D 4.2.1 to 4.2.4 (p. 1013-16, Vol. 2), frequency reuse includes changing polarization as well. There are three channel frequency bands (A, B, and C) over the nodes. The polarization of the channels frequencies in the adjacent nodes is changed. This is found on page D.4.2.3.
The point-to-multipoint communication system of Langston application provides service to a large number of subscribers in each node. The upstream signals from the shared frequencies between subscribers located in adjacent sectors incur interference, especially when the transmit power levels are unbalanced and when heavy rain cells occur in the desired subcarrier path.